Krill corresponds to a group of small and abundant marine crustaceans in the order Euphausiaceae, living in the South Antarctic Ocean. The Antarctic krill, in particular those that live at the Antarctic and sub-Antarctic regions, are composed of 11 Euphausia species, being dominant Euphausia superba, Dana and Euphausia crystallorophias. 
Several efforts have been made to produce phospholipids-enriched krill oils containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) associated to low-fat krill meal at an industrial scale. Several different cooking temperatures, different decanting torque, strong pressing, using two decanting steps, washing the first decanter solids with stick water before the second decanter, electro-plasmolysis and several other methodologies have been tested. However, see for example, U.S. Pat. Nos. 8,772,516 and 8,609,157 which provide methods to extract phospholipids-enriched krill oil based on physical-mechanical steps associated to a krill meal plant without the use of organic and/or inorganic solvents.
From the current traditional krill meal processing layouts used on board some factory trawlers, only a very small amount of krill oil is manufactured. This krill oil is usually enriched in neutral lipids with very low or undetectable amount of phospholipids. Normally, during the traditional on board (at-sea) krill process, fresh krill is heated using an indirect steam heating cooker with a rotating screw conveyor, followed by twin-screw pressing and drying. The press liquid obtained by the twin-screw press is passed through a decanter to remove the insoluble solids. The clarified decanter liquid is then used to feed separators centrifuges to separate the krill oil normally enriched with neutral lipids and astaxanthin. In this traditional process the phospholipids are bound to the proteins in the press cake. Therefore, phospholipids are usually found associated to the krill meal.
When non-traditional krill meal-processing layout is used on board at sea, it results in a similar situation as explained above. Normally, the non-traditional krill meal plant considers a contherm cooker system, a two-phase decanter or three-phase decanter and a drier. These decanters are used for de-watering and de-fatting the cooked krill. The decanter liquid is used to feed the centrifuge separators to obtain usually a neutral lipid-enriched krill oil with low or undetectable levels of phospholipids. In this case, the phospholipids are also bound to the proteins in the decanter solids. As described above, phospholipids are found in the krill meal.
Currently all phospholipids-enriched krill oil production processes are operated through on-land extraction technologies either based on whole fresh, frozen krill or dried krill meal as raw materials. This is due to the fact that these processes are solvent-based and consequently strictly forbidden to operate on-board fishing vessels.